The largest known class of neurotransmitters is comprised of peptides. The identification of new neuropeptides and the determination of their physiological roles and pathophysiological actions will lead to the development of new pharmacological approaches for the treatment of neurological disease. A neuropeptide, angel dustin, recently identified in this lab and isolated form porcine brain extracts, is an endogenous agonist for the phencyclidine receptor. Phencyclidine (1-(phenylcyclohexyl peperidine), PCP or angel dust use in man often results in clinical manifestations which include euphoria, aggressive behavior and psychotic disturbances which resemble schizophrenia. Angel dustin appears to be a PCP receptor agonist as it has identical electrophysiological actions on rat cortical and hippocampal cells as does PCP; like PCP it also causes contralateral rotation after microinjection in the substantia nigra. It therefore appears likely that in addition to having actions on higher level cortical processes, angel dust may also have actions on extrapyramidal motor systems. If, in fact, angel dust is an endogenous ligand for the phencyclidine receptor, disorders of this neuronal system could lead to psychopathologies or motor disorders and development of antagonists to this compound could lead to the discovery of a new class of antipsychotic agents. Thymosin and bombesin are two peptides originally identified in non-nervous tissues. Studies in this lab have characterized these peptides in the central nervous system using high pressure liquid chromatography and determined the distribution of these peptides using radioimmunoassay and immunocytochemistry. Thymosin in the brain appears to be highly concentrated in the hypothalamus. Bombesin immunoreactivity in the brain may be due to gastrin-releasing peptide, a concentrations of bombesin are in the hypothalamus where bombesin-containing perikarya emanate from the suprachiasmatic nucleus, a region known to regulate circadian rhythms in mammals.